Identifying the root cause of EMC Compliance

Problems at a PCB level

Ruska Patton Director of Product Management Photo

Goes

Here

Agenda

• Radiated Emissions Testing

• Very-Near-Field Implementation

• High Resolution Scanner

• Sample Results

• Far Field Prediction

• Conclusion

EMSCAN Introduction

World Leading Developer of Fast Magnetic

Very-Near-Field Measurement Applications

Real-Time Visual Test Solutions for Antenna

and PCB Designers and Verification

Engineers

Pre-Compliance Not Compliance

EMSCAN Products

EMxpert

– EMC/EMI diagnostic tool

enabling designers to rapidly

diagnose and solve EM

problems in a single design

cycle in their own lab

environment

RFxpert

– APM tool enabling engineers

to quickly evaluate and

optimize their designs with

real-time antenna

performance characterization

at their desk

OVERVIEW

Radiated Emissions Testing

Existing Solutions

• Chambers – Slow testing

• Compliance

– High CAPEX (in-house)

• Real-estate

• Qualified technicians

– High OPEX (third party)

• Probes – Slow testing

– Resolution nm

• Simulation software – Time consuming to customize per PCB

– Extensive training required

Every EMI (electromagnetic interference) problem ultimately

starts or ends at an electronic circuit

Daryl Gerke and Bill Kimmel

IN COMPLIANCE MAGAZINE JULY 2013

PCB Radiated EMC Issues

• EMC prevention an

afterthought

• Little interest in EMC

• EMC as a black art

A BETTER SOLUTION

Very-Near-Field Implementation

Scanning Array of Probes

• 1218 probes in a 29 x 42 array

• Magnetic field loop probes

– Sensitive down to -135 dBm

– Inefficient for EMI isolation

– Broadband

• 7.5 mm to 0.12 mm resolution

• Scan area 21.8cm x 31.6cm

• Real-time measurements ( <1

sec)

System Configuration

External Trigger

USB LAN/USB

Control RF

Sensor Array

Spectrum Analyzer Controller

Software Application

Spectral Scan Identify the frequencies of emission

Spatial Scan Visualize where the emissions are coming from

BEST OF BOTH WORLDS

High Resolution Scanner

Higher Resolution Spatial Scan Probe spacing is 7.5mm

Move the entire probe array to synthesize small

probe spacing

Up to Level 7 (0.1mm)

7.5mm

Level

2

Level

1

Higher Resolution Spatial Scan

• Detail of small feature available

• Even inside components like ICs Level

1 Level

3

FOLLOWING EMISSIONS ACROSS A PCB

Sample Results

Analyzing a PCB

• First view of a scan give spectral content and aggregate spatial

content

Analyzing a PCB

• Jump around by frequency or location to follow signals

• Load new PCB layers to correlate to features

Energy coupled onto power plane Energy coupled onto control line

Analyzing a PCB • Able to follow the signal on the traces as it goes between layers.

Layer 1

Layer 2

Layer 3

Via transition

to layer 2

Digital control

line on layer 1 Control line

continued on layer 2

Beginning of ground

plane shielding

control line

PEERING INSIDE AN IC

Sample Results

Emissions From Inside the IC

• Small PIC with die exposed

• About 2 minutes per scan

100 MHz 120MHz 130MHz

Emissions From Inside the IC

• Intel SSD

• Start with spectral emissions

Emissions From Inside the IC

• Then analyze spatial distribution

Comparable to Other Techniques

Probe Array

Method

Single

Probe

Method

BOARD LEVEL AND IC LEVEL

Combining both worlds

Board Level Testing

• Quick scan identifies many emissions

• Isolate by location or by frequency

Board Level Testing

• Highlight on IC and identify relevant frequencies

IC Level Testing

• Go to high resolution

• Identify which frequencies are related

264MHz

50-500MHz

231MHz 363 MHz

TYPICAL EMC CONCERNS

Other Applications

Real-Time

• Changes in real-time

• Intermittent events

• Functional testing

• Different operating modes

• Firmware modifications

A/B Comparison • Obsolescence management

• Production unit versus gold standard

• Fault diagnosis

Effectiveness of Filters Immediate feedback means trial and error can be used

Testing Shielding or Absorbers Look for leakage points or new radiation mechanisms

Test uniformity and effectiveness

Strong Emissions from

Inductor and ICs

Emissions reduced with

small ferrite tile

Non-EMC Applications

• Coexistence

– PIM 1st to 3rd harmonic 120 dBc

– Self-interference (de-sense)

• NFC

CHAMBER PREDICTIONS

Impact for EMC Compliance

Far-Field Prediction

• VNF results to predict Open Area Test Site (OATS) or free

space radiated EMI of PCB

Measure Very-Near-Field • Measure the very-near-field emission from real source

• Use this as a source model in a simulation package

• Amplitude and phase needed

Import into Simulation

Near-field source

region Source magnetic fields at 1

GHz

• A complex simulated source is replaced with simple surface

Far-Field Prediction • Simulation could include large scale effect like cables, enclosures,

etc.

3m

VERY-NEAR-FIELD ARRAY BASED MEASUREMENT

Conclusion

Very-Near-Field Pros and Cons

• Strengths

– Continuous peak hold scan for spurious events

– Real-time view of emission sources and currents

– Fast pre-compliance regulatory data

• Limitations

– PCB diagnostic not product compliance

– DUT no bigger than scanner for pre-compliance

• Any size for diagnostic

– Mezzanine PCB might need disassembly for testing

Exciting Value Proposition

Substantially Reduce Project Development

Costs

Dramatically Increase Designer Productivity

Significantly Accelerate Time-to-Market

1 Hour in a Chamber or 1 Second with a

Scanner?

Thank You

If you are interested in testing your PCB on the EMxpert system for free please contact us at

www.emscan.com

info@emscan.com

Don’t miss our Test Bootcamp!

November 16, 2016

www.emclive2016.com

Thanks for attending!